Penilaian Stabilitas Timbunan dan Potensi Kebocoran Lindi Akibat Pengaruh Seismik di Tempat Pembuangan Akhir Ngipik, Gresik

Fitri, Siti Nurlita (2018) Penilaian Stabilitas Timbunan dan Potensi Kebocoran Lindi Akibat Pengaruh Seismik di Tempat Pembuangan Akhir Ngipik, Gresik. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

TPA Ngipik di Gresik terletak dibeberapa lajur sesar aktif di Jawa Timur, sehingga besar kemungkinan wilayah ini terjadi gempa bumi. TPA ini tidak mempunyai sistem pengolahan sampah yang baik dan timbunan sampah sudah mencapai ketinggian 12 dan 10 m, sehingga perlu adanya suatu penelitian tentang potensi kerusakan apabila terjadinya gempa. Data primer pada penelitian ini didapatkan melalui pengujian fisis dan mekanis pada 3 titik bore, pengukuran mikrotremor dengan metode HVSR dilakukan dengan membagi area menjadi grid dengan jarak per 25m untuk mendapatkan efek tapak loal akibat gempa. Dilakukan pemodelan dengan Plaxis untuk mengetahui nilai shear strain dari tanah dasar dibawah timbunan dan Geoslope untuk mengetahui nilai safety factor dari lereng timbunan sampah. Untuk mengantisipasi potensi kerusakan akibat gempa, dilakukan pemodelan dengan merubah tanah dasar dengan parameter clay liner yang diatur oleh Environmental Protection Agency (EPA) dalam tiga kondisi, yaitu merubah tanah dasar disekitar timbunan setebal 1m, 2m dan merubah seluruh tanah dasar dibawah timbunan setebal 2m. Dari hasil penelitian didapatkan tanah dasar berupa lempung-lanau dengan ketebalan sedimen berkisar 42-136 m, nilai indeks kerentanan tanah 2.5 - 28, dan nilai shear strain sebesar 10-3- 10-2 untuk PGA = 0.2g. Nilai shear strain terbesar dari hasil Plaxis dan analisis mikrotremor terdapat pada area Timur-Tenggara dan Barat laut penelitian. Nilai shear strain yang tinggi merepresentasikan potensi kerusakan yang lebih besar saat terjadinya gempa. Nilai shear strain hasil plaxis lebih dapat diandalkan dengan perbedaan sebesar 55% dari pengukuran mikrotremor. Nilai SF eksisting pada saat kondisi gempa berkisar 0.57 -0.91. Penggunaan clay liner setebal 1m dan 2m mengakibatkan penuruan shear strain masing-masing sebesar 2 - 19% dan 17 - 33% dan penngkatan safety factor masingmasing sebesar 1-15% dan 2-18% dari kondisi eksisting saat terjadinya gempa. Apabila diganti secara keseluruhan dibawah timbunan setebal 2m menyebabkan penuruan shear strain sebesar 23-40% dan peningkatan safety factor 4-27% dari kondisi eksisting ketika terjadi gempa. =========== TPA Ngipik is one of the area in East java which has a several active fault. Therefore, this region could cause an earthquake caused by these faults. TPA Ngipik has a problem in waste management system. It does not have a protection layer to prevent groundwater pollution. The height of waste reached 10 m and 12m. This research present the results of the Plaxis and Geoslope and mikrotremor analysis of surface’s shear strain and safety factor due to seismic effect causing leakage of leachate. In this research, soil investigation was conducted to estimate physical, mechanical, and dynamic soil properties. Dynamic soil properties test was used microtremor. Physical and mechanical properties was performed on 3 bore with a certain depth and microtremor testing had been done by dividing the area into a grid with distance 25m. The data is processed by HVSR method to get the soil dynamic parameter. Then, the results of physical, mechanical and dynamic parameters was modeled with Geoslope to determine safety factor of landfill and Plaxis to determine the shear strain of seismic effect arise on the layer of clay under the surface. In addition, the surface layer was modeled with clay liner parameter according to Environmental Protection Agency (EPA) with 1 and 2m around the landfill, and 2m below the landfill. The bedrock depth ranges between 42-136 m with silty-clay soil. The vulnerability index (Kg) varies from 2.5 to 28, and shear strain ranges between 10-3 - 10-2 . The vulnerability index (Kg) is indicated the soil damage level due to ground motions. The weak zone, failed during earthquake was identified by the highest Kg and shear strain value. The shear strain from Plaxis Analysis is more reliable than Microtremor measurement with 55% different result. Area with highest Kg and shear strain is southwest and southeast. Safety factor of landfill in initial condition range 0.57-0.91 during the earthquake. The replacement of Clay liner with 1 and 2m thickness around the landfill was decrease shear strain about 2-19% and 17-33% and improve safety factor 1-15% and 2-18% from the initial condition, and decrease shear strain 23-40% and increase safety factor 4-27% with replacement of 2m thickness below the landfill.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Landfill; Mikrotremor; HVSR; Shear strain; Tempat pembuangan akhir; Mikrotremor; Shear strain; Ngipik, Gresik.
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
T Technology > TD Environmental technology. Sanitary engineering > TD767.7 Sewage sludge treatment and disposal
T Technology > TD Environmental technology. Sanitary engineering > TD789 Refuse and refuse disposal
Divisions: Faculty of Civil Engineering and Planning > Environment Engineering > (S2) Master Theses
Depositing User: Siti Nurlita Fitri
Date Deposited: 09 Jul 2018 04:58
Last Modified: 09 Jul 2018 04:58
URI: http://repository.its.ac.id/id/eprint/52084

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